Hypothermia in the mountains

ByEduardo Azcona

Looking through the newspaper archives we can see that every year in Spain, hypothermia is behind some of the victims in the mountains. It is enough to type the right words into Google to realise that this is not an isolated case.

Outside our mountains, surely you all remember the case of the 21 runners who died during the course of an ultra-marathon in China in May 2021, just over two years ago. A tragedy that could have been avoided, in which all the necessary ingredients for hypothermia to occur coincided.

What is hypothermia?

Hypothermia is defined as a decrease in core body temperature (CBT), the inner core of the body, to below 35°C. It occurs when the body loses more heat than it is able to generate and in severe cases can lead to death.

Mechanisms of body heat loss

Body heat is dissipated in various ways:

  • By radiation or cession: there is a loss of energy or radiated heat between the body and the colder environment or objects. It is usually caused by unprotected surfaces such as the head and neck, where up to 30% of body heat can be lost.
  • By convection: mainly due to the wind. It is also essential not to leave skin uncovered. You may be interested in this other article on thermal sensation by cold or wind.
  • By driving: when it comes into contact with another cold body. Water is an excellent conductor, i.e. body heat is lost much faster in contact with cold water than with cold air.
  • By evaporation: through sweat and breath. Increases in dry and windy weather conditions.

Main causes of hypothermia in the mountains

  1. Prolonged exposure to cold environments: it is more common to suffer hypothermia in an environment that is not too cold but with strong wind, blizzard, humidity, or when ill-equipped, than in more obvious situations, with extremely low temperatures, if it is for a short period of time.
  2. Inadequate clothing and unprotected body surface: it is of great importance to choose the appropriate clothing, to cover the head and neck and to use the correct combination of the layer system.
  3. Wet clothes: body heat is lost much faster in contact with cold water. Water is an excellent conductor.
  4. Dehydration: in severe cold, the body may try to rid itself of fluids by urinating. It is important to drink hot or cold liquids, the main thing is to hydrate. Avoid alcohol, coffee, tea and other diuretic drinks. In this article we talk about the hydration in the mountains and the importance of isotonic drinks.
  5. Lack of energy supply: calorie-dense foods with high sugar content are recommended.
  6. Exhaustion.
  7. Impossibility of movement: physical activity generates heat. Situations may occur where it is very difficult or impossible to move because of an accident, precarious situation, etc.

Degrees of hypothermia and its symptoms.

The International Commission for Emergency Mountain Medicine (ICAR MEDDCOM) and the Medical Commission of the International Union of Mountaineering Associations (UIAA MEDDCOM) have established a practical method based on clinical signs and their relationship to core body temperature that divides hypothermia into five degrees:

  • Mild hypothermia: prior to Grade I hypothermia, between 35°C and 37°C, the subject begins to feel cold and starts shivering. If no remedy is taken and the temperature drops below 36ºC, the symptoms continue to worsen with more intense shivering but which we are still able to control, cold skin, apathy, negative attitude and loss of motor coordination. We are unable to perform complex manoeuvres with our hands such as tying our boot laces or operating apparatus.
  • Grade I: the core body temperature drops to between 35 and 32°C. The tremors become more intense, impossible to control, there is numbness and the skin turns blue/grey. The individual is confused, sluggish, experiences (irrational) behavioural changes and motor coordination worsens. If the situation continues to worsen, there is a progressive loss of tremor, numbness, lack of reflexes and difficulty breathing.
  • Grade II: the core body temperature drops to between 32ºC and 28ºC. This is a medical emergency that is difficult to reverse without the appropriate means. The victim still has vital signs, is drowsy, tremors cease and reflexes are very weak. Confusion is total and hallucinations may occur. Circulatory collapse occurs and no pulse is palpable at the wrist, although it is palpable at the neck.
  • Grade III: core body temperature drops to between 28°C and 24°C. The victim is unconscious, goes into a coma and may develop severe heart problems, apnoea and appear to be dead. High danger of death due to cardiorespiratory disturbances.
  • Grade IV: body temperature drops to between 24°C and 13.7°C, the lowest temperature recorded in a successful resuscitation case. No vital signs, apparent death.
  • Grade V: core body temperature falls below 13°C. Death due to irreversible hypothermia.

Procedure in case of hypothermia

The first objective is to prevent this situation from occurring. It is important to pay attention to the members of the group in order to identify the first signs of hypothermia: shivering, fatigue, etc.

In such a case, it is necessary to know how to give up the activity. Continuing physical activity generates warmth, but can be counterproductive if fatigue is excessive. In addition, trying to reason with a person with symptoms of hypothermia can be difficult.

The procedure starts by stopping the heat loss and call 112. The first thing to try to do is to find a sheltered place safe from wind and damp. Whenever possible, change wet or damp clothing for dry clothing, and if not available, wring out wet clothing as much as possible. Next, increase the amount of warm clothing, while remembering to protect the head and neck, and keep the subject insulated from colder surfaces with anything: rucksacks, plastic sheeting, a mat, etc.

If the person is in a mild state of hypothermia and tolerates food intake, we will try to give them a hot or cold drink, the important thing is to hydrate. Repeat the operation every 15 minutes until normal urine production is restored. Avoid alcohol, coffee, tea and diuretic drinks. Later, we can give them sugary or high-energy foods.

If all of the above is not sufficient to restore body temperature, skin-to-skin contact with someone in the group who is kept warm, in a sleeping bag or wrapped in a blanket, may be necessary. If we have the possibility to heat water, we can place hot water bottles wrapped in socks between the armpits and groin. Be careful with this as there is a danger of overheating shock.

In more advanced stages, if the victim is unconscious, do not give him a drink. Avoid moving him or her or move him or her gently to avoid sending a jet of cold blood to the heart. In this state, it is necessary to treat the victim in a hospital.

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